After having carved four necks now, I think the best advice I could give is
1. Follow the pattern outlined by the video that I linked to earlier in this thread. It is by far the easiest and best way I have seen to get a constant straight carve every time. I did move my lines over about 1 mm from what he recommended because I wanted a thicker neck, but the philosophy is right on the button.
2. TAKE YOUR TIME. After you have taken off too much wood it is impossible to put back on, so measure a lot, and slow down and don't get in a hurry. It takes a lot of elbow grease and time, but is totally worth it. Stop and look at what you're doing often so you don't go too far.
I did take some more photo's of the inbetween stuff like I had promised, so here goes.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/924f1843-f56c-411d-8589-1f48f8e28d02.jpg)
Once I got the first facets carved in, I took my hand rasp and shaped in the ends fairly close. This is where you want to take your time, and just go to the line.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_200820.jpg)
Next I split the distance on the two facets, and drew two more lines down the length of the neck on each side. Make sure you sight down the length of the neck when you're done, and make sure they are evenly spaced with each other on both sides.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_201938.jpg)
Next I carved between the new lines, and the center line, stopping just short of the center line on each side.
Then take you're rask and clean up the ends as before.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_203004.jpg)
At this point, I took my rasp and just knocked off the facet points that were left, so it started to round out a little.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_204709.jpg)
At this point I use very course strips of sand paper and start working back and forth across the neck, working my way up and down the neck till it rounds out. Make sure that you are not sanding down too far so that it is getting into the rosewood. Also you want to make sure that you are applying even pressure with both hands, and working evenly. Here is where the workout starts, but take lots of breaks, and use your caliper to get the correct thickness measurements you want. It's slow going, but will come out good if you take your time and don't rush things.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_220059.jpg)
When it comes to it, I periodically use my rasp, or sandpaper on a dowel, or this oscilating sander to work in the taper you want for the headstock. I just work on it periodically as I go. Again, just take your time and go slow.
![Image](http://i686.photobucket.com/albums/vv221/CraterSoftball/Jag%20Build/20160608_221727.jpg)